ES3048642T3 - Magnetic lifting device having pole shoes with spaced apart projections - Google Patents

Abstract

A magnetic device for magnetic coupling to a ferromagnetic body comprises a housing with a central hole. A plurality of pole sectors are arranged within an envelope of the central hole, forming a contact interface with the workpiece of the magnetic device. Each sector comprises several pole portions separated by respective distances, where a recess separates each pole portion from the other pole portions. A first sector forms a first pole of the magnetic device, and a second sector forms a second pole. A first permanent magnet is included. A second permanent magnet is movable with respect to the first. An actuator is operatively coupled to the second permanent magnet to move it with respect to the first.

Description

[0001] DESCRIPTION

[0002] Magnetic lifting device having pole shoes with spaced projections

[0003] Technical field

[0004] This disclosure relates to magnetic devices. More specifically, this disclosure relates to pole shoes for switchable magnetic devices.

[0005] Background

[0006] A switchable magnetic device can be used to magnetically couple the magnetic device to one or more ferromagnetic bodies. A switchable magnetic device may include one or more magnets that can rotate relative to one or more stationary magnets to generate and derive a magnetic field. The switchable magnetic device can be attached in a removable manner, by switching the magnetic device between an "on" and an "off" state, to a ferromagnetic body (e.g., a workpiece), such as for lifting objects, material handling, material holding, magnetically engaging or coupling objects together, and other applications. US Patent 2005/012579 A1 describes a switchable magnetic device that includes a first magnet and a second magnet, both being essentially cylindrical. The magnets are housed in a casing made of pole pieces. The pole pieces are ferromagnetic. The lower magnet is fixedly mounted in the housing, while the upper magnet can rotate within the housing. The upper magnet is formed with notches or slots along its vertical side walls. These notches or slots receive downward-hanging bar arms. The bar is received within a groove formed in a protrusion. The protrusion is connected to a short bar, which, in turn, is fixedly connected to a handle or lever. By these means, rotation of the handle or lever causes the second magnet to rotate. When the upper magnet is positioned so that its north pole substantially overlaps the south pole of the lower magnet, and vice versa, the first and second magnets act as an internal active magnetic shunt, and as a result, the strength of the external magnetic field from the device is quite low. Rotating the upper magnet 180° around its axis of rotation aligns the magnets so that the respective north and south poles of the upper magnet substantially overlap the respective north and south poles of the lower magnet. With this alignment, the external magnetic field from the device is strong enough to allow it to be attached to surfaces or objects. US patent 2014/314507 A1 describes a magnetic column drill comprising a main housing, a drill unit supported by the main housing for relative movement about the drill unit's axis of rotation, and a base attached to the main housing for selective magnetic engagement with a ferromagnetic workpiece. The base includes a magnet holder, a fixed magnet assembly supported within the magnet holder, a rotating magnet assembly supported within the magnet holder, and a drive. The transmission includes an input, an output coupled to the rotating magnet assembly to rotate the rotating magnet assembly relative to the fixed magnet assembly through a predetermined rotation angle, and a gear train positioned between the output and the input. The gear train is configured to provide a variable gear ratio between the output and the input during at least a portion of the predetermined rotation angle.

[0007] Summary

[0008] The embodiments of this disclosure relate to pole shoes for a switchable magnetic device. In these embodiments, the pole shoes comprise a plurality of projections that facilitate the creation of surface magnetic fields on a ferromagnetic workpiece to be moved by the magnetic device. The surface magnetic field has sufficient holding force to lift the attached ferromagnetic workpiece and restrain it against shear forces during transport. As such, switchable magnetic devices, including the pole shoes, can be used for destacking thin materials. Aspects of this disclosure are as set forth in the accompanying claims.

[0009] Brief description of the drawings

[0010] Figure 1A illustrates a representative front view of an example magnetic switchable device in an off state.

[0011] Figure 1B illustrates a representative front view of the example magnetic switchable device depicted in Figure 1A in an on state.

[0012] Figure 1C illustrates a representative side view of the example magnetic switching device depicted in Figures 1A and 1B.

[0013] Figure 2A illustrates a representative side view of another example magnetic switching device.

[0014] Figure 2B illustrates a representative top view of the example switchable magnet depicted in Figure 2A. Figure 3 illustrates an exploded schematic view of an example switchable magnetic device with pole shoes.

[0015] Figure 4 illustrates an isometric view of the switchable magnetic device depicted in Figure 3 in the assembled state.

[0016] Figure 5A illustrates a front section view of the switchable magnetic device depicted in Figures 3 and 4 and the magnetic circuit created when the device is in an “off” state.

[0017] Figure 5B illustrates a front section view of the switchable magnetic device depicted in Figures 3 and 4 and the magnetic circuit created when the device is in the “on” state.

[0018] Figure 6 illustrates a side view of a portion of an example polar shoe.

[0019] Figure 7A illustrates a side view of a portion of another example polar shoe and Figure 7B illustrates a detailed view of a portion of the example polar shoe depicted in Figure 7A.

[0020] Figure 8 illustrates a side view of a portion of another example polar shoe.

[0021] Figures 9A-9B illustrate another example polar plate.

[0022] Figures 10A-10B illustrate another example polar plate.

[0023] Figure 11A illustrates a front view of another example magnetic switchable device.

[0024] Figure 11B illustrates a side view of the switchable magnetic device depicted in Figure 11A.

[0025] Figure 12 illustrates a processing sequence of a method of using an example switchable magnetic device with pole shoes.

[0026] Figure 13 illustrates a robotic system that includes a switchable magnetic device.

[0027] Although the disclosed content is subject to various modifications and alternative forms, the specific embodiments have been shown, by way of example, in the drawings and are described in detail below. The intent, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives that fall within the scope of the disclosure.

[0028] Detailed description of the drawings

[0029] The embodiments provided herein relate to switchable magnetic devices. Example switchable magnetic devices are described in U.S. Patent No. 7,012,495, entitled SWITCHABLE PERMANENT MAGNETIC DEVICE; in U.S. Patent No. 7,161,451, entitled MODULAR PERMANENT MAGNET CHUCK; in U.S. Patent No. 8,878,639, entitled MAGNET ARRAYS; and in U.S. Provisional Patent Application No. 62/248,804, filed October 30, 2015, entitled MAGNETIC COUPLING DEVICE WITH A ROTARY ACTUATION SYSTEM, File No. MTI-0007-01-US-E; and the provisional US patent application No. 62/252,435, filed on November 7, 2015, entitled MAGNETIC COUPLING DEVICE WITH A LINEAR ACTUATION SYSTEM, file number MTI-0006-01-US-E.

[0030] The examples illustrated herein provide exemplary switchable magnetic devices having a first permanent magnet and a second permanent magnet movable with respect to the first permanent magnet, similar to the exemplary switchable magnetic devices of patent '495. Each of the permanent magnets may be a cylindrical unit dipole body of a single type of rare-earth magnetic material, such as NdFeB or SmCo. Additional types of switchable magnetic devices may be implemented. Each type of switchable magnetic device includes at least one first permanent magnet that is movable with respect to a second permanent magnet. In addition, the exemplary switchable magnetic devices may include a first plurality of permanent magnets movable with respect to a second plurality of permanent magnets. Additionally, the example switchable magnetic devices may include at least a first permanent magnet placed inside a first housing that acts as a polar extension of at least one first permanent magnet, the first housing being movable with respect to a second housing having at least one second permanent magnet placed inside the second housing, the second housing acting as a polar extension of at least one second permanent magnet.

[0031] With reference to Figures 1A-1C, an example switchable magnetic device 10 is shown. The switchable magnetic device 10 includes an upper permanent magnet 12 and a lower permanent magnet 14 arranged in a stacked relationship in a housing 28. The permanent magnet 12 comprises a south pole portion (S-pole portion) 18 and a north pole portion (N-pole portion) 20. Similarly, the permanent magnet 14 comprises an N-pole portion 22 and an S-pole portion 24. The housing 28 may include multiple components assembled together to form a housing. Furthermore, the housing 28 may include features for maintaining the permanent magnet 12 spaced from the permanent magnet 14 or for incorporating spacers, such as the spacer 13 in the present embodiment, which maintains the permanent magnet 12 in a spaced relationship with respect to the permanent magnet 14. The spacer 13 is made of a non-magnetic material to isolate the permanent magnet 12 from the permanent magnet 14.

[0033] The pole shoes 16', 16'' are coupled to the housing 28. The pole shoes 16', 16'' are made of a ferromagnetic material and are magnetically coupled to the magnets 12, 14 through portions of the housing 28. A lower portion of each of the pole shoes 16', 16'' includes a workpiece contact interface 17', 17'' that can be made contact with a workpiece 27, for example an upper sheet 27' of ferromagnetic material from a stack of sheets 27', 27'', and 27'' of the ferromagnetic material. The workpiece contact interfaces 17', 17'' of the pole shoes 16', 16'' cooperate with the magnets 12, 14 via the pole shoes 16', 16'' and the housing 28 to form the first and second poles of the magnets 12, 14. In one example, a single unit pole shoe forms each of the pole shoes 16', 16''. In another example, a plurality of pole shoes forms each of the unit pole shoes 16', 16''.

[0035] In embodiments, the permanent magnet 14 is fixed with respect to the housing 28 and the permanent magnet 12 is movable within the housing 28 with respect to the permanent magnet 14 to alter an alignment of magnet portions 18, 20 of the permanent magnet 12 with respect to magnet portions 22, 24 of the permanent magnet 14. In the illustrated embodiment, the permanent magnet 12 can rotate with respect to the permanent magnet 14.

[0037] The switchable magnetic device 10, based on the configuration of the permanent magnets 12, 14, establishes two different magnetic circuits. In particular, the switchable magnetic device 10 establishes a first magnetic circuit called the switched magnetic device 10 on state when the permanent magnet 12 is rotated so that the S 18 pole portion of the permanent magnet 12 is adjacent to the S 24 pole portion of the permanent magnet 14, and the N 20 pole portion of the permanent magnet 12 is adjacent to the N 22 pole portion of the permanent magnet 14 (shown in Figure 1B). In the switched-on state, one or more workpieces 27 being made of a ferromagnetic material, such as iron or steel, are held by the switchable magnetic device 10 due to the completion of the magnetic circuit from the aligned N pole portions 20, 22 of the upper and lower magnets 12, 14, respectively, through the housing 28 and the pole shoe 16', through one or more sheets of workpieces 27, through the pole shoe 16'' and the housing 28, and to the aligned S pole portions 18, 24 of the upper and lower magnets 12, 14, respectively. The workpiece contact interface 17' of the pole shoe 16' functions as a north pole of the switchable magnetic device 10. The workpiece contact interface 17'' of the pole shoe 16'' functions as a south pole of the switchable magnetic device 10.

[0039] As explained in more detail herein, the size and shape of the pole shoes 16', 16'' result in the first magnetic circuit being substantially confined to the workpiece sheet 27' of the workpiece sheets 27 and having sufficient holding force to vertically lift the workpiece sheet 27' in direction 33 relative to the rest of the workpiece sheets 27. The switchable magnetic device 10 can therefore operate to unstack the workpiece sheets 27. Of course, in some embodiments, a portion of the magnetic flux supplied to the workpiece sheets 27 by the switchable magnetic device 10 may enter the lower sheet 27'' of the workpiece sheets 27, but not to a level that results in the lower sheet 27'' being lifted by the switchable magnetic device 10 together with the workpiece sheet 27'. Therefore, as used herein, the fact that the first magnetic circuit is substantially limited to the workpiece sheet 27' of the workpiece sheets 27 means that the amount, if any, of magnetic flux from the switchable magnetic lifting device 10 entering the lower sheet 27'' is below a level that would result in the lower sheet 27'' being lifted vertically in direction 33 by the switchable magnetic lifting device 10 together with the workpiece sheet 27'.

[0041] The switchable magnetic device 10 establishes a second magnetic circuit called the switchable magnetic device 10 off state when the permanent magnet 12 is rotated so that the N pole portion 18 of the permanent magnet 12 is adjacent to the S pole portion 22 of the permanent magnet 14, and the S pole portion 20 of the permanent magnet 12 is adjacent to the N pole portion 24 of the permanent magnet 14 (shown in Figure 1A). In the off state, one or more workpieces 27 made of a ferromagnetic material, such as iron or steel, are not retained by the switchable magnetic device 10 due to the completion of a magnetic circuit between the switchable magnetic device 10 and the workpiece sheets 27. This circuit is formed by the alignment of the S-pole portion 18 of magnet 12 with the N-pole portion 22 of magnet 14, and by the alignment of the N-pole portion 20 of magnet 12 with the S-pole portion 24 of magnet 14. In other words, the alignment of magnets 12 and 14 results in a substantially derived magnetic circuit within the switchable magnetic device 10, which causes the collapse of the external magnetic field. In one example, at least 96% of the magnetic flux produced by magnets 12 and 14 is retained in the switchable magnetic device 10 when the device is in the off state. In another example, at least 99% of the magnetic flux produced by magnets 12, 14 is retained at the workpiece contact interfaces 17', 17''.

[0043] Referring back to Figure 1A, the switchable magnetic device 10 includes a coupling portion 30 and an actuator 32. The coupling portion 30 couples the actuator 32 to the permanent magnet 12 so that the actuator 32 can reorient the permanent magnet 12 with respect to the permanent magnet 14. Example coupling portions 30 include one or more recesses in the permanent magnet 12 and/or a housing supporting the permanent magnet 12, one or more protrusions extending from the permanent magnet 12 and/or a housing supporting the permanent magnet 12, and/or one or more connections or gear systems coupled to the permanent magnet 12 and/or a housing supporting the permanent magnet 12. Example actuators include rotary actuators and linear actuators, each of which, via the coupling portion 30, can impart a rotation to the permanent magnet 12.

[0045] Example coupling portions and actuators are disclosed in U.S. Patent No. 7,012,495, entitled SWITCHABLE PERMANENT MAGNETIC DEVICE; in U.S. Patent No. 7,161,451, entitled MODULAR PERMANENT MAGNET CHUCK; in U.S. Patent No. 8,878,639, entitled MAGNET ARRAYS; U.S. Provisional Patent Application No. 62/248,804, filed October 30, 2015, entitled MAGNETIC COUPLING DEVICE WITH A ROTARY ACTUATION SYSTEM, File No. MTI-0007-01-US-E; and the provisional US patent application No. 62/252,435, filed on November 7, 2015, entitled MAGNETIC COUPLING DEVICE WITH A LINEAR ACTUATION SYSTEM, file number MTI-0006-01-US-E.

[0047] In embodiments, the actuator 32 is coupled to an electronic, pneumatic, or hydraulic controller 34 that controls the operation of the actuator 32 and thus the alignment of the permanent magnet 12 with respect to the permanent magnet 14 through the coupling portion 30. As illustrated in Figure 1A, the controller 34 includes a processor 36 with an associated computer-readable medium, for example, memory 38. The memory 38 includes magnetic coupler state logic 40 which, when executed by the processor 36, causes the electronic controller 34 to instruct the rotary actuator 32 to move the permanent magnet 12 so that the magnetic switchable device 10 is placed in one of the on state and the off state. The term “logic,” as used herein, includes software and/or firmware running on one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, digital signal processors, hardwired logic, or combinations thereof. Therefore, in accordance with the embodiments disclosed herein, various logics may be implemented in any appropriate manner and remain in conformity with the embodiments disclosed herein. A non-transient, machine-readable medium comprising logic may further be considered to be incorporated within any tangible form of a computer-readable medium, such as solid-state memory, magnetic disk, and optical disk, containing an appropriate set of computer instructions and data structures that would cause a processor to perform the techniques described herein. This disclosure contemplates other embodiments in which the state logic of the magnetic coupler is not microprocessor-based, but is configured to control the operation of the switchable magnetic device 10 based on one or more hard-wired instruction sets and/or software instructions stored in memory 38. In addition, the controller 34 may be contained within a single device or be a plurality of networked devices to provide the functionality described herein.

[0049] In embodiments, the electronic controller 34 changes the state of the magnetic switchable device 10 in response to an input signal received from an input device 42. Example input devices include switches, buttons, touchscreens, microphones, sensors, controllers, and other devices through which an operator can provide one of a tactile, auditory, or visual input command. For example, in one embodiment, the magnetic switchable device 10 is attached to one end of a robotic arm, and the input device 42 is a network interface through which the controller 34 receives instructions from a robot controller on when to place the magnetic switchable device in one of an on and an off state. Example network interfaces include a wired network connection and an antenna for a wireless network connection. While the embodiments described above relate to electronic, pneumatic, or hydraulic actuation, in alternative embodiments the magnetic switchable device 10 may be manually actuated. Example manual actuators include handles, knobs, and other devices that can be operated by a human operator.

[0051] With reference to Figure 1C, the polar shoes 16', 16'' (illustrated polar shoe 16'') include a plurality of projections 44 and recesses 46 separating the projections 44. In embodiments, the polar shoes 16', 16'' may include any number of recesses 46 and any number of projections 44 arranged on each side of the recesses 46. The plurality of recesses 46 are dimensioned to prevent workpieces 27 from entering the respective recesses 46. As such, an interface 17 for a workpiece 27 is collectively formed by the projections 44. In one example, each of the polar shoes 16', 16'' has a first number of projections 44 and a second number of recesses 46 interposed between the first number of projections, the second number being at least two. In one variation of this, the second number is at least three. In a further variation of this, the second number is at least five.

[0053] As a result of the projections 44 and the recesses 46, the switchable magnetic device 10 produces an external magnetic field 50 (shown in Figure 1B) that is more concentrated closer to the interface 17 than an external magnetic field that would be produced by the same magnetic device 10 if the pole shoes 16', 16'' did not include the projections 44 and the recesses 46. More specifically, as illustrated in Figure 1B, the external magnetic field 50 passes substantially through the first workpiece 27' while substantially none of the magnetic field 50 passes through the second workpiece 27'' or/or the third workpiece 27'''. Although the magnetic field 50 illustrates that substantially none of the magnetic field 50 passes through the second workpiece 27'', some of the magnetic field 50 may leak into the second workpiece 27''. Conversely, if the pole shoes 16', 16'' did not include the projections 44 and the recesses 46, then the external magnetic field 50 would likely penetrate deeper into the workpiece sheet stack 27, the second workpiece sheet 27'', and/or the third workpiece sheet 27'''. This would reduce the possibility of the upper workpiece sheet 27' being unstacked from the second workpiece sheet 27''.

[0055] Tables 1 and 2 illustrate the average breaking strength of switchable magnetic devices on workpieces of varying thicknesses. Specifically, Table 1 illustrates switchable magnetic devices having a first type of magnet, wherein a first switchable magnetic device of the switchable magnetic devices having a first type of magnet has pole shoes that do not have projections 44 and a second switchable magnetic device 10 of the switchable magnetic devices having a first type of magnet has pole shoes 16', 16'' that do have projections 44. Table 2 illustrates switchable magnetic devices having a second type of magnet, wherein a first switchable magnetic device of the switchable magnetic devices having a second type of magnet has pole shoes that do not have projections 44 and a second switchable magnetic device 10 of the switchable magnetic devices having a second type of magnet has pole shoes 16', 16'' that do have projections 44.

[0057]

[0060]

[0063] As shown in the data, the magnetic switching device 10 with pole shoes 16', 16'' with 44 projections has a higher average breaking strength on thinner workpieces than the magnetic switching device with pole shoes without projections. Furthermore, as the workpiece thickness increases, the magnetic switching device 10 with pole shoes 16', 16'' with 44 projections has a lower overall average breaking strength.

[0064] As a result of the magnetic field 50 being concentrated near the interface 17 of the pole shoes 16', 16'', a magnetically switchable device 10 that includes the pole shoes 16', 16'' with projections 44 and recesses 46 provides better destacking capabilities compared to the same magnetically switchable device 10 that would include pole shoes without the projections or recesses. For example, the magnetically switchable device 10 that includes the pole shoes 16', 16'' having projections 44 and recesses 46 may be more capable of destacking thin metal sheets (e.g., 0.5 mm metal sheet, 1 mm metal sheet, 2 mm metal sheet, and/or the like) than the same magnetically switchable device 10 that had pole shoes that did not include projections 44 or recesses 46.

[0065] Additionally, the dimensions of the projections 44 and the recesses 46 can be further configured to produce variable magnetic field intensities near the interface 44. That is, the additional concentration of the magnetic field 50 near the interface 17 of the pole shoes 16', 16'' can be achieved by lengthening the pole shoes 16', 16'' relative to the housing 28 and thus relative to the magnets 12, 14. In embodiments, the upper and lower magnets 12, 14 and the housing 28, which serves as a pole extension piece for the magnets 12, 14, can have an outer shell defined by a height 52 (see Figure 1B) of the housing 28, a width 54 (see Figure 1B) of the housing 28 extending on each side of a centerline 55 of the switchable magnetic device 10, and a length 58 (see Figure 1C) of the housing 28. As shown in Figure 1B, the pole shoe 16' is arranged on one side of the centerline 55 of the switchable magnetic device 10, and the pole shoe 16'' is arranged on an opposite side of the centerline 55 of the switchable magnetic device 10. In one example, the pole shoes 16', 16'' extend beyond at least one of the height 52, width 54, and/or length 58 of the housing 28. In the illustrated embodiment, the pole shoes 16', 16'' extend beyond the height 52 (below the housing 28, see Figure 1B), width 54 (positioned outside the housing 28, see Figure 1B), and length 58 (both in front of and behind the housing 28, see Figure 1B). 1C) of the casing wrapping 28.

[0066] In some embodiments, the distance 60 (shown in Figure 1A) between the lower portion of the housing 28 and the interface 17 of the pole shoes 16', 16'' and/or the length 62 of the pole shoes 16', 16'' (shown in Figure 1C) can be varied to produce different magnetic field intensities near the interface 17, described below with reference to Figures 11A, 11B.

[0067] Although the embodiments disclosed in connection with Figures 1A-1C included an upper magnet 12 and a lower magnet 14, in alternative embodiments the switchable magnetic device 10 may comprise more than one upper magnet 12 and more than one lower magnet 14. An example of this type is shown in Figures 2A and 2B.

[0068] Figure 2A is a representative side view of another example switchable magnetic device 10'; and Figure 2B is a representative top view of the switchable magnet 10'. As illustrated in Figures 2A and 2B, the switchable magnetic device 10' includes a plurality of upper permanent magnets 12 and a plurality of lower permanent magnets 14, by way of example three upper magnets 12', 12'', 12''' and three lower magnets 14', 14''', 14'''. The upper and lower magnets 12', 14' form a first set of magnets 56'. The upper and lower magnets 12'', 14'' form a second set of magnets 56''. The upper and lower magnets 12''', 14''' form a third set of magnets 56'''. The magnet assemblies 56', 56'', 56''' are separated from each other.

[0069] Each set of magnets 56', 56'', 56''' produces a magnetic field that propagates from the respective N poles of the magnet sets 56', 56'', 56''' through the pole shoes 16', 16'' to the respective south poles of the magnet sets 56', 56'', 56'''. In embodiments where the magnetic device 10' is in an on state, the magnetic field extends through the workpiece 27' when the workpiece 27' is in contact with the interface 17 of the pole shoes 16', 16''. When the magnetic device 10' is off, the magnetic field is substantially confined internally to the magnetic device 10'. Although the pole shoes 16', 16'' are illustrated spanning the magnet assemblies 56', 56'', 56''' in alternative embodiments, the switchable magnetic device 10' may include multiple pole shoes 16', 16'' that collectively span the magnet assemblies 56', 56'', 56'''. Additionally or alternatively, the switchable magnetic device 10' may include 2, 4, 5, etc., magnet assemblies 56', 56'', 56'''.

[0070] Although the switchable magnetic device 10 is described as being in a stacked relationship, other switchable magnetic devices that do not have magnets in a stacked relationship may be used together with the pole shoes 16', 16''. Example non-stacked switchable magnetic devices are described in U.S. Patent Application No. 15/803,753, filed November 4, 2017, entitled MAGNET ARRAYS.

[0071] Further details of an example switchable magnetic device 100 are discussed below in relation to Figures 3 and 4. In particular, Figure 3 is an exploded schematic view of an example switchable magnetic device 100 with ferromagnetic pole shoes 102', 102'', and Figure 4 is an isometric view of the switchable magnetic device 100 in an assembled state. Further details regarding the magnetic device 100 are provided in U.S. Provisional Application No. 62/517,057, filed June 8, 2017, entitled ELECTROMAGNET-SWITCHABLE PERMANENT MAGNET DEVICE.

[0072] During the description of Figures 3 and 4, reference will also be made to Figure 5A, which is a front section view of the magnetic switchable device 100 and the magnetic circuit created when the device is in its first configuration, i.e., the off state. Additionally, reference must also be made to Figure 5B, which is a front section view of the magnetic switchable device 100 when the device is in its second configuration, i.e., the on state.

[0073] The magnetic device 100 can have a plurality of configurations that result in the establishment of different magnetic circuits. For example, switching the magnetic device 100 from a second configuration (shown in Figure 3 and Figure 5a), where the magnetic device 100 establishes a second magnetic circuit, to a first configuration (shown in Figure 5B), where the magnetic device 100 establishes a first magnetic circuit, can couple a ferromagnetic body to the magnetic device 100 via the pole shoes 102', 102'', as explained below.

[0074] The magnetic device 100 comprises a central housing 104. The central housing 104 includes two ferromagnetic housing components (e.g., steel) 106, 108, which can be joined by fasteners (not shown). The housing components 106, 108 can be further or alternatively joined using other methods and materials (e.g., epoxy, locating features (projections, notches, chamfers, molded keyways, and/or the like), etc.). The housing component 106 may be referred to herein as the upper housing component 106, and the housing component 108 may be referred to herein as the lower housing component 108. In addition, the pole shoes 102', 102'' can be attached to the housing 104 with fasteners (not shown).

[0075] In embodiments, the housing components 106, 108 may be a rectangular parallelepiped block of low-reluctance ferromagnetic material. A cylindrical cavity 110 may extend through the upper housing component 106 and a cylindrical cavity 112 may extend through the lower housing component 108. The cylindrical cavities 110, 112 may be perpendicular to the upper faces 114, 116 of the respective housing components 106, 108. The cylindrical cavity 110 may be referred to herein as the upper cylindrical cavity 110 and the cylindrical cavity 112 may be referred to herein as the lower cylindrical cavity 112. In embodiments, the cylindrical cavities 110, 112 may respectively receive the magnets 118, 120. The magnet 118 may be referred to herein as the upper magnet 118 and the magnet 120 may be referred to herein as the lower magnet 120.

[0076] The upper housing component 106 has two side walls 124', 124'' and the lower housing component 108 has two side walls 126', 126''. In embodiments, the side walls 124', 124'' of the upper housing component 106 and the side walls 126', 126'' of the lower housing component 108 may have a thickness that contains the magnetic field generated by the magnets 118, 120 within the housing components 106, 108 when the magnetic device 100 is in the first configuration (shown in Figure 5A). In embodiments, the upper magnet 118 has an N-S axis 128 and the lower magnet 120 has an N-S axis 130. Magnets 118, 120 may be NdFeB magnets and the active magnetic mass and magnetic properties of magnets 118, 120 may be equal and/or exact within achievable manufacturing tolerances and permanent magnet magnetization technologies.

[0077] In embodiments, the lower magnet 120 is received and secured against rotation in the lower cylindrical cavity 112 such that the N-S axis 130 extends from side wall 126' to side wall 126''. As a result, side walls 126', 126'' are magnetized according to the active magnetic pole adjacent to them. That is, side wall 126' is magnetized as an N pole, while side wall 126'' becomes an S pole. In contrast, because the upper magnet 118 can rotate freely about axis 122, in the absence of pole shoes 102', 102'', the polarity of side walls 124', 124'' would be determined by the relative rotational position and orientation of the upper magnet 118.

[0078] As stated above, the upper magnet 118 is configured to rotate from the orientation shown in Figure 3. In embodiments, the upper magnet 118 can rotate between 180 and 185 degrees to a rotational position where its N pole coincides with the N pole of the lower magnet 120 and, conversely, the S poles overlap each other (see Figure 5B). When the N-S axes 128, 130 are oriented parallel, both side walls 124', 126' will be magnetized with the same North magnetic polarity, as will the adjacent pole shoe 102'. Furthermore, the side walls 124'', 126'' will be magnetized with the same South magnetic polarity, as will the adjacent pole shoe 102''. This reorientation of the upper magnet 118 will create an “active” working air gap at the lower axial contact interface of the workpiece 132', 132'' of the pole shoes 102', 102'', thereby allowing a closed low-reluctance magnetic circuit to be created. In particular, the closed low-reluctance magnetic circuit originates and terminates at magnets 118, 120, through side walls 124', 124'', 126', 126'', the pole shoes 102', 102'', and a ferromagnetic body that may be touching both contact interfaces of the workpiece 132', 132'' of the pole shoes 102', 102''. This state may be referred to herein as if the magnetic device 100 were in an “on” state (see Figure 5B). Conversely, in the state where the N-S axes 128, 130 are oriented antiparallel, a closed magnetic circuit is formed within the magnetic device 100 and the magnetic device 100 can be said to be in an off state (see Figure 5A).

[0080] The upper cylindrical cavity 110 may have a smooth wall surface and a diameter that allows the upper magnet 118 to be received therein so that it can rotate with minimal friction about the N-S axis 128 and preferably maintain a minimal air gap. In embodiments, a friction-reducing coating may be applied to the upper cylindrical cavity 110. The lower cylindrical cavity 112 may have a rough wall surface and a diameter that provides an interference fit with the lower magnet 120 so that when the lower magnet 120 is mounted within the lower cylindrical cavity 112, it maintains its rotational orientation and is prevented from axial and rotational displacement under the operating conditions of the magnetic device 100. Additionally or alternatively, other mechanisms, such as bonding or additional cooperating form-fit components (not shown), may be used to secure the lower magnet 120 within the lower cylindrical cavity 112.

[0082] A circular disc 134 made of ferromagnetic material can be disposed at the bottom of the lower cylindrical cavity 112. The circular disc 134 can support the lower magnet 120. In embodiments, the circular disc 134 can be press-fitted or otherwise secured to close the lower end of the lower cylindrical cavity 112 to seal the lower cylindrical cavity 112 and the lower magnet 120 against contamination on a working face 136 of the magnetic device 100. The ferromagnetic nature of the circular disc 134 can help complete the magnetic circuit by providing additional magnetizable material between the side walls 126', 126'', so that the field of the lower magnet 120 couples exclusively with the magnetic material provided in the lower housing component 108 and the pole shoes 102', 102'' to form a magnetic circuit in either the on or off state. This also allows the Magnetic Device 100 to operate with greater clamping force when it is on and cancels any clamping force when it is off.

[0084] In embodiments, a support structure 138 may be located between the magnets 118 and 120. The support structure 138 may support the upper magnet 118 within the upper cylindrical cavity 110. Additionally or alternatively, the support structure 138 may facilitate the maintenance of a specified axial distance between the lower circular face of the upper magnet 118 and the upper circular face of the lower magnet 120. In embodiments, the support structure 138 may include a circular lower plate 140 of non-magnetic metallic material, a swivel bearing 142, and a non-magnetic circular upper plate 144. In embodiments, the lower plate 140 rests on the upper face of the lower magnet 120 and closes the open upper end of the lower cylindrical cavity 112. In embodiments, the lower plate 140 may be temporarily mounted on the open end of the lower cylindrical cavity 112. The swivel bearing 142 It may be seated in a suitably sized cylindrical depression (or seat) on an upper surface of the lower plate 140. The diameter of the upper plate 144 is such that it can rotate within the lower axial end of the upper cylindrical cavity 110. That is, the upper plate 144 may have a diameter similar to that of the upper magnet 118, which seats with its lower axial end face in the upper plate 144. In embodiments, an upper face of the upper plate 144 may be coated with a sliding PTFE coating, and a lower face of the upper plate 144 may include a shaft protrusion or trunnion (not shown). In embodiments, the shaft journal can be seated within the inner ring bearing portion of the slewing bearing 142. Additionally or alternatively, a non-magnetic circular cover (e.g., aluminum) (not shown) can be mounted on the upper housing component 106 to cover the upper cylindrical cavity 110.

[0086] In embodiments, the support structure 138 can be replaced by a different type of arrangement, wherein the upper magnet 118 is secured against a stem 146 while allowing free rotation of the stem, by means of a retaining clip ring (not shown) secured in an annular groove (not shown) near a lower end of the stem 146.

[0088] In embodiments, the stem 146 penetrates through a hole 148 in the upper magnet 118, so that the upper magnet 118 can rotate coaxially about the stem 146. In embodiments, the stem 146 projects perpendicularly from a central hub portion 152 of a cap component 150, so that positioning the stem 146 by installing the cap component 150 cooperates with the upper magnet 118 to ensure its concentric rotation within the cylindrical cavity of the upper housing component 106. In the illustrated embodiments, the stem 146 is a cylindrical pin welded or otherwise fixed to the cap component 150.

[0090] In embodiments, the cover component 150 may be non-magnetizable and comprise a rectangular plate 154 with an arched window 156. In embodiments, the rectangular plate 154 may be machined to have a footprint similar to that of the housing components 106, 108, i.e., rectangular. Opposite end ends of the arched window 156 provide “hard stops” for a rotation-stop block member 158 that is fixed to the upper magnet 118 so that the block member 158 can move within the arched window 156 during rotation of the upper magnet 118 when the magnetic device 100 is switching between configurations. In embodiments, the arched window 156 may include a latching mechanism 160 that functions to maintain an intermediate rotational state of the upper magnet 118 between the hard stops provided by the ends of the arched window 156. Therefore, the upper magnet 118 can be fixed in intermediate rotational positions relative to the lower magnet 120. Additionally or alternatively, the latching mechanism 160 may be included in the upper housing component 106 or another portion of the magnetic device 100.

[0092] In one embodiment, the stem 146 is coupled to an actuator 32 that moves the upper magnet 118 to various positions relative to the lower magnet 120. In the illustrated embodiment, one or more solenoid coil bodies 162 surround the upper housing 106 and orient the upper magnet 118 relative to the lower magnet 120 by means of one or more currents passing through the solenoid coil body 162. The solenoid coil body 162 may consist of wrapped (or otherwise arranged) enamel-coated wire windings. In embodiments, the enamel-coated wires may be composed of one or more conductive materials (for example, copper, silver, gold, and/or the like).

[0094] The cap component 150 may be further configured to support/house various control and power electronics associated with and required to supply current to the solenoid coil body 162 to rotate the upper magnet 118, as described below. Alternatively, the cap component 150 may include contact leads for connection to a power supply (not shown) that supplies current to the solenoid coil body 162. In embodiments, the cap component 150 may be secured to the upper housing component 106 using bolts or other types of fasteners.

[0096] In embodiments, a power supply (not shown) can be connected to the solenoid coil body 162 by means of a suitable control circuit to supply a current to the solenoid coil body 162. In response to the current supplied to the solenoid coil body 162, the solenoid coil body 162 produces a magnetic field. In embodiments, the magnetic field produced by the solenoid coil body 162 is oriented so as to produce a torque on the upper magnet 118. The torque rotates the N-S shaft 128 of the upper magnet 118 from a first configuration (shown in Figure 5A) to the second configuration (shown in Figure 5B). Additionally or alternatively, the upper magnet 118 can be stopped in various intermediate configurations by means of the latching mechanisms 160.

[0098] In embodiments, the magnets 118 and 120 may have different magnetization and coercivity properties. For example, the lower magnet 120 may consist of a high-coercivity permanent magnet, which cannot be easily demagnetized by an external magnetizing influence, and the upper magnet 118 may consist of a medium- or low-coercivity magnetic element. Consequently, the magnetic field produced by the solenoid coil body 162 may affect the upper magnet 118 to a greater degree than the lower magnet 120.

[0100] In embodiments, the solenoid coil body 162 may comprise multiple solenoid coil bodies. For example, the solenoid coil body 162 may comprise two solenoid coil bodies that are electrically insulated from each other and extend from one corner of the upper housing component 106, diagonally across one top face of the upper housing component 106 to the opposite corner of the upper housing component 106 and under the upper housing component 106 to complete one winding. The respective coils can be wound diagonally across the upper housing component 106 and the cap component 150, with one coil winding over the other, so that they form an 'X' of windings when viewed in the top plan view of the upper housing component 106. Although the magnetic device 100 is described herein as being electrically driven by the solenoid coil body 162, the magnetic device 100 can be driven by an electric actuator through a mechanical connection, such as a motor, pneumatic actuator, hydraulic actuator, or manual actuator, in embodiments.

[0102] As illustrated, threaded holes 164 can be cut in the side walls 124', 124'', 126', 126''. The threaded holes 164 can facilitate the attachment of the pole shoes 102', 102'' to the housing components 106, 108 by means of screws or clamping bolts (not shown). That is, fastening screws or bolts can be inserted through countersunk through holes 166 of the pole shoes 102', 102'', the spacing of which is equal to that of the threaded holes 164. In this way, both housing components 106, 108 can be connected to pole shoes 102', 102'' in a manner that provides a low-reluctance magnetic circuit path, substantially free of air gaps between the magnets 118, 120, the side walls 124', 124'', 126', 126'', and the pole shoes 102', 102''.

[0104] The pole shoes 102', 102'' provide a ferromagnetic contact interface of the workpiece for the magnetic device 100. In embodiments, the pole shoes 102', 102'' may be composed of a ferromagnetic material with low magnetic reluctance. Although the pole shoes 102', 102'' are represented as having a parallelepiped plate shape, they may have other shapes, which can be based on the shape of a workpiece to which the magnetic device 100 will be attached. An example is the cylindrical shape shown in Figures 9A-9B, which matches a cylindrical workpiece shape, such as a pipe. Another example is the V-shape shown in Figures 10A-10B, which coincides with the edges or corners of a workpiece.

[0105] As illustrated, the pole shoes 102', 102'' include portions 168', 168” positioned close to the housing components 106, 108. As stated above, these portions 168', 168” are secured to the housing components 106, 108 by one or more fastening devices (e.g., screws, etc.). Additionally, the pole shoes 102', 102'' comprise a plurality of protrusions 170', 170'', also referred to herein as projections. The plurality of protrusions 170', 170'' collectively form the workpiece contact interfaces of the pole shoes 102', 102''. In embodiments, the pole shoes 102', 102'' that include the plurality of projections 170', 170'' create a more superficial magnetic field than the pole shoes that have a flat workpiece contact interface, as explained in the examples provided herein.

[0107] Figure 6 is a side view of a portion of an example pole shoe 200 that can serve as pole shoe 132'; or pole shoe 132'' of the magnetic device 100. The pole shoe 200 comprises a first portion 202 that can be positioned near the housing (e.g., the housing 104) of a magnetic device (e.g., the magnetic device 100). The pole shoe 200 may also include holes 204 extending through the pole shoe 200 to releasably secure the pole shoe 200 to a housing of a magnetic device via a clamping mechanism (e.g., clamping screws, etc.). Furthermore, the polar shoe 200 includes a plurality of projections 206 arranged on a lower portion 208 of the polar shoe 200. Each of the projections 206 is separated by recessed portions 210. Additionally, the plurality of projections 206 collectively form a contact interface with the workpiece 212 of the polar shoe 200.

[0108] As stated above, due to the plurality of projections 206 included on the pole shoe 200, a magnetic device including a pole shoe 200 produces a stronger magnetic field near the contact interface 212 of the workpiece than a magnetic device including a pole shoe having a continuous, flush lower profile. The magnetic field produced near the contact interface 212 of the workpiece may be referred to herein as the surface magnetic field. Likewise, by including the plurality of projections 206 on the pole shoe 200, a magnetic device including a pole shoe 200 produces a weaker magnetic field at a greater depth within the pole shoe 200 than a magnetic device including a pole shoe with a continuous, flush lower profile. The magnetic field produced farther from the pole shoe 200 may be referred to herein as the far or deep magnetic field produced by the pole shoe 200. Put another way, a magnetic device including a pole shoe 200 having projections 206 has a stronger clamping force near the contact interface 212 of the workpiece than a magnetic device including a pole shoe with a continuous flush interface that does not include projections 206.

[0110] In embodiments, the surface magnetic field and the far-field magnetic field of a pole shoe 200 may depend on the type of pole shoe 200. In particular, the surface magnetic field may be the magnetic field produced from the contact interface of the workpiece 212 to a distance from the contact interface of the workpiece 212 that is approximately equal to the width 214 of the projections 206. For example, if the widths 214 of the projections 206 are 2 mm, then the surface magnetic field is the magnetic field produced from the contact interface of the workpiece 212 to a depth of 2 mm from the contact interface of the workpiece 212. Likewise, the far-field magnetic field produced in this example is the magnetic field produced at a depth greater than 2 mm from the contact interface of the workpiece 212.

[0112] Because a magnetic device 100 produces a stronger surface magnetic field and a weaker far-field magnetic field due to the pole shoe projections 206, the magnetic device 100 can be used to destack thin ferromagnetic bodies better than a magnetic device 100 having a pole shoe without the projections 206. That is, a magnetic device 100 including a pole shoe that does not have the projections 206 can produce a stronger far-field magnetic field, which will result in multiple thin ferromagnetic bodies coupling to the magnetic device. When attempting to obtain a single thin ferromagnetic body from a stacked array of thin ferromagnetic bodies, this is an undesirable result. As such, instead of using a magnetic device that includes a pole shoe without the 206 projections for unstacking ferromagnetic bodies, a pole shoe 200 that includes the 206 projections can be used.

[0114] In embodiments, varying the widths 214 of the projections 206 results in different surface magnetic fields produced by the same magnetic device. In embodiments, to produce a preferred surface magnetic field for a specific ferromagnetic body, the widths 214 of the projections 206 can be within approximately ±25% of the thickness of the ferromagnetic body to be destacked. For example, when a magnetic device destacks ferromagnetic sheets 2 mm thick, the widths 214 of the projections 206 could be approximately 2 mm (e.g., 2 mm ±25%). In embodiments, this will produce a strong surface magnetic field between 0 mm and 2 mm deep from the contact interface 212. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic bodies having thicknesses less than the limit. That is, for ferromagnetic bodies with a thickness less than X mm, a preferred surface magnetic field can be produced by projections 206 having widths 214 that are at a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic body with a thickness of 14 * X mm, the widths 214 of the projections 206 can be at the lower bound of X mm instead of ±25% of 14 * X mm. If, however, the thickness of the ferromagnetic body is X mm or more, then the widths 214 can be approximately equal (for example, ±25%) to the thickness of the ferromagnetic body. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is only an example and is not intended to be limiting.

[0116] In at least one embodiment, when a magnetic device including a pole shoe 200 is coupled to ferromagnetic bodies having different thicknesses, a pole shoe 200 having widths 214 that are an average of the thickness of the ferromagnetic bodies can be used to reduce the need to change the pole shoes. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied such that if the average thickness of the ferromagnetic bodies is below the lower limit (i.e., <2.0 mm), the widths 214 can be configured to be the lower limit (i.e., 2.0 mm).

[0118] In embodiments, varying the depths 216 and/or widths 218 of the recesses 210 results in different surface magnetic fields produced by the same magnetic device 100. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic body, the depths 216 and/or widths 218 of the recesses 210 could be approximately equal (for example, ±25%) to the widths 214 of the projections 206. For example, if the widths 214 of the projections 206 are 2 mm, then the depths 216 and/or widths 218 of the recesses 210 could be approximately 2 mm (for example, 2 mm ±25%). In embodiments, this will produce a strong surface magnetic field between 0 mm and 2 mm deep from the contact interface 212. Similar to the above, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic bodies having thicknesses less than the limit. That is, for ferromagnetic bodies having a thickness less than X mm, a preferred surface magnetic field can be produced by depths 216 and widths 218 that are at a lower limit of X mm but not less than the lower limit. That is, to produce a preferred magnetic field for a ferromagnetic body having a thickness of 14 * X mm, the depths 216 and widths 218 can be at the lower limit of X mm instead of ±25% of ^ * X mm. If, however, the thickness of the ferromagnetic body is X mm or more, then the depths 216 and widths 218 can be approximately equal (for example, +-25%) to the thickness of the ferromagnetic body.

[0120] Similar to the above, when a magnetic device 100 including a pole shoe 200 is coupled to ferromagnetic bodies of varying thicknesses, a pole shoe 200 with recess depths 216 and/or widths 218 of recesses 210 that average the thickness of the ferromagnetic bodies can be used to reduce the need to change pole shoes. Alternatively, a lower limit (e.g., 2.0 mm) can be applied such that if the average thickness of the ferromagnetic bodies is below the lower limit (i.e., <2.0 mm), the depths 216 and widths 218 can be set to the lower limit (i.e., 2.0 mm).

[0122] As stated above, the pole shoe 200 can be releasably coupled to a magnetic device housing. Therefore, when the projections 206 of the pole shoe 200 do not have the appropriate widths 214, depths 216, and/or widths 218 for the ferromagnetic body to which the magnetic device 100 is coupled, the pole shoe 200 can be replaced with a more suitable pole shoe 200.

[0124] Figure 7A is a side view of a portion of another example pole shoe 300 that can serve as pole shoe 132'; or pole shoe 132'' of the magnetic device 100, and Figure 7B illustrates a detailed view of a portion of the example pole shoe depicted in Figure 7A. Similar to the pole shoe 200 depicted in Figure 6, the pole shoe 300 comprises a first portion 302 that can be positioned close to a housing (e.g., the housing 104) of a magnetic device (e.g., the magnetic device 100). The pole shoe 300 can also include holes 304 extending through the pole shoe 300 to releasably secure the pole shoe 300 to the housing 104 of the magnetic device 100 by means of a clamping mechanism (e.g., clamping screws, etc.). Furthermore, the polar shoe 300 includes a plurality of projections 306 arranged on a lower portion 308 of the polar shoe 300. Each of the projections 306 is separated by a recessed portion 310. The plurality of projections 306 collectively form a contact interface with the workpiece 312 of the polar shoe 300.

[0126] Similar to the above, varying the widths 314 of the projections 306 and/or the depths 316, and/or the widths 318 of the recesses 310 results in different surface magnetic fields produced by the same magnetic device 100. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic body, the widths 314 of the projections and/or the depths 316, and/or the widths 318 of the recesses 310 could be approximately equal (for example, ±25%) given the thickness of the ferromagnetic body to be coupled to the magnetic device 100. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic bodies having thicknesses less than the limit. That is, for ferromagnetic bodies with a thickness less than X mm, a preferred surface magnetic field can be produced by widths 314, depths 316, and/or widths 318 that are at a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic body with a thickness of *X mm, the widths 314, depths 316, and/or widths 318 can be at the lower bound of X mm instead of ±25% of *X mm. If, however, the thickness of the ferromagnetic body is X mm or more, then the widths 314, depths 316, and/or widths 318 can be approximately equal (e.g., ±25%) to the thickness of the ferromagnetic body. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is just one example and is not intended to be limiting.

[0128] Alternatively, when a magnetic device including the 300 pole shoe is coupled to ferromagnetic bodies of varying thicknesses, a 300 pole shoe having widths 314, depths 316, and/or widths 318 that are approximately the average thickness of the ferromagnetic bodies can be used to reduce the need to change pole shoes. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied so that if the average thickness of the ferromagnetic bodies is below the lower limit (i.e., <2.0 mm), the widths 314, depths 316, and/or widths 318 can be set to be the lower limit (i.e., 2.0 mm).

[0130] In embodiments, the upper portions 319 of the pole shoe 300 have a continuous slope profile (the slope is defined at all points, without sharp corners). By way of example, the upper corners 319 of the pole shoe 300 may have a rounded shoulder portion 320. A magnetic device 100 that includes a pole shoe 300 having a rounded shoulder 320 has been shown to have a higher magnetic flux transfer to a ferromagnetic body than a magnetic device that has a pole shoe with sharp corners. Accordingly, in at least one embodiment, the upper corners 319 of the polar shoe 300 include rounded shoulder portions 320. In one example, the radius of curvature 322 of the rounded shoulder portion 320 can preferably range from 1% to 75% of the height 323 of the polar shoe 300. In another example, the radius of curvature 322 can preferably range from 25% to 75% of the height 323 of the polar shoe 300. In a further example, the radius of curvature 322 can preferably be in the range of 40% to 60% of the height 323 of the polar shoe 300.

[0132] With reference to Figure 7B, additionally or alternatively, the recessed portions 310 between the projections 306 may have a continuous slope profile (the slope is defined at all points, without sharp corners) at their upper ends. Similar to having a rounded shoulder 320, a magnetic device including a pole shoe 300 having curved recessed portions 310 may have a greater magnetic flux transfer to a ferromagnetic body than a magnetic device including a pole shoe having recessed portions with sharp corners. In embodiments, to provide high magnetic flux transfer, the bend radius 324 of the curved recess portions 310 can be approximately half the width 318 of the recesses 310. Test data have indicated that an improvement of more than 3% can be obtained by including a slope profile of the recess portions 310 that is half the width 318 of the recesses 324.

[0134] Figure 8 is a side view of a portion of another example pole shoe 400 that can serve as pole shoe 132'; or pole shoe 132'' of the magnetic device 100. Similar to the pole shoes 200, 300 depicted in Figures 6 and 7A-7B, respectively, the pole shoe 400 comprises a first portion 402 that can be positioned close to a housing (e.g., the housing 104) of a magnetic device (e.g., the magnetic device 100). The pole shoe 400 can also include holes 404 extending through the pole shoe 400 to releasably secure the pole shoe 400 to a housing of a magnetic device via a clamping mechanism (e.g., clamping screws, etc.). Furthermore, the polar shoe 400 includes a plurality of projections 406 arranged on a lower portion 408 of the polar shoe 400. Each of the projections 406 is separated by recessed portions 410. The plurality of projections 406 collectively form a contact interface with the workpiece 412 of the polar shoe 400.

[0136] Similar to the above, varying the widths 414 of the projections 406 and/or the depths 416, and/or the widths 418 of the recesses 410 results in different surface magnetic fields produced by the same magnetic device 100. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic body, the widths 414 of the projections 406 and/or the depths 416, and/or the widths 418 of the recesses 410 could be approximately equal (for example, ±25%) to the thickness of the ferromagnetic body. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic bodies having thicknesses less than the limit. That is, for ferromagnetic bodies with a thickness less than X mm, a preferred surface magnetic field can be produced by widths 414, depths 416, and/or widths 418 that are at a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic body with a thickness of X mm, the widths 414, depths 416, and/or widths 418 can be at the lower bound of X mm instead of ±25% of X mm. If, however, the thickness of the ferromagnetic body is X mm or more, then the widths 414, depths 416, and/or widths 418 can be approximately equal (for example, ±25%) to the thickness of the ferromagnetic body. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is just one example and is not intended to be limiting.

[0137] Alternatively, when a magnetic device including pole shoe 400 is coupled to ferromagnetic bodies having different thicknesses, a pole shoe 400 having widths 414, depths 416, and/or widths 418 that are an average of the thickness of the ferromagnetic bodies can be used to reduce the need to change pole shoes. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied so that if the average thickness of the ferromagnetic bodies is below the lower limit (i.e., <2.0 mm), the widths 414, depths 416, and/or widths 418 can be set to be the lower limit (i.e., 2.0 mm).

[0139] In embodiments, the pole shoe 400 may also include compressible members 420 arranged between projections 406 in the recessed portions 410. In embodiments, the compressible members 420 are compressed when the magnetic device 100 comprising the pole shoe 400 is coupled to a ferromagnetic body. Due to the compression of the compressible members 420, static friction is created between the compressible members 420 and the ferromagnetic body that is potentially greater than the static friction between the projections 406 and the ferromagnetic body. As such, a ferromagnetic body coupled to a magnetic device 100 that includes the pole shoe 400 may be less likely to rotate and translate than if the ferromagnetic body were coupled to a pole shoe that did not include the compressible members 420. In embodiments, the compressible members 420 may be composed of an elastic material such as isoprene polymers, polyurethane, nitrile rubber, and/or the like.

[0141] Figures 9A-9B represent another example pole plate 500 that can be used as a pole shoe 132' or pole shoe 132'' of the magnetic device 100. Similar to the pole plates 200, 300, 400 shown in Figures 6, 7A-7B and 8, the pole plate 500 includes a plurality of projections 502 arranged on a lower portion 504 of the pole plate 500. Each of the projections 502 is separated by recessed portions 506. The plurality of projections 502 collectively form a workpiece contact interface 508 of the pole plate 500.

[0143] As illustrated, the contact interface of workpiece 508 is not flat. In embodiments, the non-flat workpiece contact interface 508 can facilitate the coupling of a magnetic coupling device 100 to a ferromagnetic workpiece having a non-flat surface. For example, a magnetic coupling device 100 including a pole plate 500 can be used to couple the magnetic coupling device 100 to one or more types of rods, stems, etc. (e.g., a camshaft). While the contact interface of workpiece 508 includes a curved surface 510, the contact interface of workpiece 508 can have any other type of non-flat surface. For example, the contact interface of workpiece 508 can include a contour similar to that of a ferromagnetic workpiece to which the magnetic coupling device including the contact interfaces of workpiece 508 is intended to be coupled.

[0145] Despite having a non-planar workpiece contact interface 508, varying the widths 512 of the projections 502 and/or the depths 514, and/or the widths 516 of the recesses 506 results in different surface magnetic fields produced by the same magnetic coupling device. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic workpiece, the widths 512 of the projections 552 and/or the depths 514, and/or the widths 516 of the recesses 506 could be approximately equal (for example, ±25%) to the thickness of the ferromagnetic workpiece. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic workpieces having thicknesses less than the limit. That is, for ferromagnetic workpieces with a thickness less than X mm, a preferred surface magnetic field can be produced by widths 512, depths 514, and/or widths 516 that are within a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic workpiece 102 having a thickness of X mm, the widths 512, depths 514, and/or widths 516 can be within the lower bound of X mm instead of ±25% of X mm. If, however, the thickness of the ferromagnetic workpiece is X mm or more, then the widths 512, depths 514, and/or widths 516 can be approximately equal (for example, ±25%) to the thickness of the ferromagnetic workpiece. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is just one example and is not intended to be limiting.

[0147] Alternatively, when a magnetic coupling device including pole plate 500 is coupled to ferromagnetic workpieces of varying thicknesses, a pole plate 500 having widths 512, depths 514, and/or widths 516 that average the thickness of the ferromagnetic workpieces can be used to reduce the need to change pole plates. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied such that if the average thickness of the ferromagnetic workpieces 102 is below the lower limit (i.e., <2.0 mm), the widths 512, depths 514, and/or widths 516 can be set to be the lower limit (i.e., 2.0 mm).

[0149] Figures 10A-10B represent another example pole plate 550 that can be used as a pole shoe 132' or pole shoe 132'' of the magnetic device 100. Similar to the pole plates 200, 300, 400, 500 shown in Figures 6, 7A-7B, 8, 9A-9B, the pole plate 550 includes a plurality of projections 552 arranged on a lower portion 554 of the pole plate 550. Each of the projections 552 is separated by recessed portions 556. The plurality of projections 552 collectively form a workpiece contact interface 558 of the pole plate 550.

[0151] As illustrated, the contact interface of the workpiece 558 is not flat. In embodiments, the non-flat workpiece contact interface 558 can facilitate the coupling of a magnetic coupling device 100 to a ferromagnetic workpiece having a non-flat surface. For example, a magnetic coupling device including a pole plate 550 can be used to couple the magnetic coupling device 100 to one or more edges, corners, etc., of a ferromagnetic workpiece. While the contact interface of the workpiece 558 includes two downward-sloping surfaces 560 extending from a central point 562, the contact interface of the workpiece 558 can have any other type of non-flat surface. For example, the contact interface of workpiece 558 may include a contour similar to that of a ferromagnetic workpiece to which the magnetic coupling device including the contact interfaces of workpiece 558 is intended to be coupled.

[0153] Despite having a non-planar workpiece contact interface 558, varying the widths 564 of the projections 552 and/or the depths 566, and/or the widths 568 of the recesses 556 results in different surface magnetic fields produced by the same magnetic coupling device. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic workpiece, the widths 564 of the projections 552 and/or the depths 566, and/or the widths 568 of the recesses 556 could be approximately equal (for example, ±25%) to the thickness of the ferromagnetic workpiece. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic workpieces having thicknesses less than the limit. That is, for ferromagnetic workpieces with a thickness less than X mm, a preferred surface magnetic field can be produced by widths 564, depths 566, and/or widths 568 that are within a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic workpiece having a thickness of X mm, the widths 564, depths 566, and/or widths 568 can be within the lower bound of X mm instead of ±25% of X mm. If, however, the thickness of the ferromagnetic workpiece is X mm or more, then the widths 564, depths 566, and/or widths 568 can be approximately equal (e.g., ±25%) to the thickness of the ferromagnetic workpiece. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is just one example and is not intended to be limiting.

[0155] Alternatively, when a magnetic coupling device including pole plate 550 is coupled to ferromagnetic workpieces 102 having different thicknesses, a pole plate 550 having widths 564, depths 566, and/or widths 568 that are an average of the thickness of the ferromagnetic workpieces can be used to reduce the need to change pole plates. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied so that if the average thickness of the ferromagnetic workpieces is below the lower limit (i.e., <2.0 mm), the widths 564, depths 566, and/or widths 568 can be set to be the lower limit (i.e., 2.0 mm).

[0157] Figure 11A is a front view of an example magnetic switchable device 600, and Figure 11B is a side view of the magnetic switchable device 600. The magnetic device 600 includes pole shoes 602', 602'' and a housing 604. In embodiments, the magnetic device 600 may have some or all of the same features and/or functionalities as the magnetic device 100, and the pole shoes 602', 602'' may have some or all of the same features and/or functionalities as the pole shoes 102', 102''. Additionally or alternatively, the pole shoes 602', 602'' may have some or all of the same features as the pole shoes 200, 300, 400 depicted in Figures 6, 7, and 8, respectively. For example, the pole shoes 602', 602'' comprise a first portion 606 that can be positioned close to the housing 604. The pole shoes 602', 602'' may also include holes 608 extending through the pole shoes 602', 602'' to releasably secure the pole shoes 602', 602'' to the housing 604 by means of a fastening mechanism (e.g., clamping screws, etc.). Furthermore, the pole shoes 602', 602'' include a plurality of projections 610 arranged on a lower portion 612 of the pole shoes 602', 602''. Each of the projections 610 is separated by a recessed portion 614. The plurality of projections 610 included in the polar shoe 602' collectively form a contact interface with the workpiece 616' of the polar shoe 602' and the plurality of projections included in the polar shoe 602'' collectively form a contact interface with the workpiece 616'' of the polar shoe 602''.

[0159] Furthermore, varying the widths 618 of the projections 622 and/or depths 620, and/or the widths 622 of the recesses 614 results in different surface magnetic fields produced by the same magnetic device 600. In embodiments, to produce a surface magnetic field suitable for a specific ferromagnetic body, the widths 618 of the projections 622 and/or the depths 620, and/or the widths 622 of the recesses 614 could be approximately equal (for example, ±25%) to the thickness of the ferromagnetic body. In at least one embodiment, however, there may be a limit to producing a preferred surface magnetic field for some ferromagnetic bodies having thicknesses less than the limit. That is, for ferromagnetic bodies with a thickness less than X mm, a preferred surface magnetic field can be produced by widths 618, depths 620, and/or widths 622 that are within a lower bound of X mm but not less than the lower bound. In other words, to produce a preferred magnetic field for a ferromagnetic body with a thickness of X mm, the widths 618, depths 620, and/or widths 622 can be within the lower bound of X mm instead of ±25% of X mm. If, however, the thickness of the ferromagnetic body is X mm or more, then the widths 618, depths 620, and/or widths 622 can be approximately equal (for example, ±25%) to the thickness of the ferromagnetic body. Examples of a lower bound can be in the range of 0 mm to 2 mm. However, this is just one example and is not intended to be limiting.

[0161] Alternatively, when the magnetic device 600 is used to couple to ferromagnetic bodies of varying thicknesses, the widths 618 of the projections 622 and/or the depths 620, and/or the widths 622 of the recesses 614 that average the thickness of the ferromagnetic bodies can be used to reduce the need to change the pole shoes. Similar to the above, however, a lower limit (e.g., 2.0 mm) can be applied such that if the average thickness of the ferromagnetic bodies is below the lower limit (i.e., <2.0 mm), the widths 618, depths 620, and/or widths 622 can be set to be the lower limit (i.e., 2.0 mm).

[0163] Although the polar footings 602', 602'' shown do not include rounded shoulders (e.g., rounded shoulder 320) and/or curved recessed portions (e.g., curved recessed portion 310), in alternative embodiments, the polar footings 602', 602'' may include one or both of these features. Additionally or alternatively, although the polar footings 602', 602'' shown do not include compressible members (e.g., compressible members 420), in alternative embodiments, the polar footings 602', 602'' may include one or both of these features.

[0165] As illustrated, the pole shoes 602', 602'' have respective thicknesses 624', 624''. In embodiments, different thicknesses 624', 624'' can produce different surface magnetic fields and far-field magnetic fields by means of the magnetic device 600. That is, similar to the widths 618 of the projections 610, the thicknesses 624', 624'' are approximately equal to the thickness of a ferromagnetic body to which the magnetic device 600 is coupled to produce a surface magnetic field suitable for destacking the ferromagnetic body. For example, when the magnetic device 600 is destacking ferromagnetic sheets 2 mm thick, the thicknesses 624', 624'' could be approximately 2 mm (e.g., 2 mm ±25%). In embodiments, this will produce a strong surface magnetic field between 0 mm and 2 mm. In embodiments, the 602', 602'' pole shoes may be composed of 304 stainless steel and/or include aluminum surrounding at least a portion of the 602', 602'' pole shoes to add structural integrity to the 602', 602'' pole shoes. In embodiments, this may be particularly advantageous when the 602', 602'' pole shoes have thin 624', 624'' thicknesses (e.g., less than or equal to 5 mm).

[0167] Additionally or alternatively, the housing 604 may include an offset 626 from the workpiece contact interfaces 616', 616''. In embodiments, the offset 626 may depend on the magnetic field produced by the magnetic device 600. That is, in embodiments, the offset 626 may be a percentage of the depth of the surface magnetic field produced by the magnetic device 600. Additionally or alternatively, the offset 626 may be a percentage of the workpiece thickness. For example, if the magnetic device 600 is configured to produce a surface magnetic field within the workpiece that has a depth of X mm and/or to engage with a workpiece that has a thickness of X mm, then the offset 626 may be a percentage (greater or less than 100%) of X. In one example, the offset 626 may preferably be in the range of 100% to 700% of the depth of the surface magnetic field. In another example, the displacement 626 may preferably be in the range of 200% to 600% of the surface magnetic field depth. In a further example, the displacement 626 may preferably be in the range of 300% to 500% of the surface magnetic field depth. In yet another example, the displacement 626 may preferably be in the range of 350% to 400% of the surface magnetic field depth.

[0169] Additionally or alternatively, the pole shoes 602', 602'' may extend along the direction 628 by distances 630, 632 beyond a front face 634 and a rear face 636 of the housing 604, respectively. Put another way, the width 637 of the pole shoes 602', 602'' may be greater than the depth 638 of the housing 604. Extending beyond the front and rear faces 634, 636, the contact area between the workpiece contact interfaces 616', 616'' and the ferromagnetic body. The increased contact area of the workpiece contact interfaces 616', 616'' can increase the clamping force and/or shear force of the magnetic device 600. For example, the distance 630, distance 632, and/or width 637 can be varied depending on the ferromagnetic body being clamped by the magnetic device 600. That is, depending on the preferred clamping force for a ferromagnetic body, the distance 630, distance 632, and/or width 637 can be varied to achieve the preferred clamping force. As another example, the distance 630, distance 632, and/or width 637 may be a percentage (greater or less than 100%) of the depth 638 of the housing 604. In one example, the distance 630 and/or distance 632 may preferably be in the range of 25% to 75% of the depth 638 of the housing 604. In another example, the distance 630 and/or distance 632 may preferably be in the range of 35% to 65% of the depth 638 of the housing 604. In yet another example, the distance 630 and/or distance 632 may preferably be in the range of 45% to 55% of the depth 638 of the housing 604.

[0170] The thickness 640 of the polar shoes 602', 602'' can also be varied. Similar to increasing the width 637 of the polar shoes 602', 602'', increasing the thickness 640 of the polar shoes 602', 602'' increases the contact area between the contact interfaces of the workpiece 616', 616'' and the ferromagnetic body. The increased contact area of the workpiece contact interfaces 616', 616'' can increase the clamping force and/or shear force of the magnetic device 600. Consequently, the thickness 640 can be varied depending on the desired clamping force of the magnetic device 600. In one example, the thickness 640 can approximately match the thickness of a ferromagnetic body that the magnetic device 600 is clamping. In another example, the thickness 640 can vary relative to the width 637. That is, depending on the ferromagnetic body that the magnetic device 600 is clamping, it may be preferable to maintain a certain surface area of the contact interface 616', 616'' and, therefore, a certain clamping force of the magnetic device 600. As such, as the width 637 increases, the thickness 640 can decrease, and vice versa. Therefore, if a clamping force and a wider pole shoe 616', 616'' are preferred for a ferromagnetic body, the preferred clamping force can be maintained by decreasing the thickness 640 and increasing the width 637.

[0171] In the embodiments provided above, any of the features of the pole shoes 16, 132, 200, 300, 400, 500, 550, and 602 may be used together. Additionally or alternatively, any of the projections and recesses of the pole shoes 16, 132, 200, 300, 400, 500, 550, and 602 may be integrated into the housings of the magnetic devices 10, 100, and 600 instead of being attached to them.

[0172] Furthermore, as described above, when the projection widths and recess depths/widths exceed a lower limit, and the projection widths and recess depths/widths of the pole shoes approximately match the thickness of the ferromagnetic body, pole shoes having these characteristics produce the strongest clamping force for a ferromagnetic body that has approximately the same thickness as the projection widths and recess depths/widths. Figure 12 is a flowchart of a Method 700 for using an example switchable magnetic device with pole shoes. Method 700 comprises contacting a ferromagnetic body with a first pole shoe, as depicted in Block 702. In embodiments, the first pole shoe may be releasably attached to a housing of a magnetic device. Additionally, the magnetic device may be capable of establishing two different magnetic circuits. The first magnetic circuit can be referred to as the magnetic device being in an on state, and the second magnetic circuit can be referred to as the magnetic device being in an off state.

[0173] In embodiments, the first pole shoe, the housing, and the magnetic device may have features equal to or similar to the pole shoes 16, 102, 200, 300, 400, 500, or 602; the housings 28, 104, and 604; and the magnetic devices 10, 100, and 600, respectively, depicted above. For example, the ferromagnetic body may make contact with the first pole shoe via a workpiece contact interface, wherein the workpiece contact interface of the first pole shoe includes a plurality of projections. Additionally or alternatively, the magnetic device may comprise: a first permanent magnet mounted within the housing having a pair of active N-S poles and a second permanent magnet having a pair of active N-S poles. In embodiments, the second permanent magnet can be rotatably mounted within the housing in a stacked relationship with the first permanent magnet, wherein the second permanent magnet can rotate between a first and a second position. Additionally or alternatively, the magnetic device can establish a plurality of magnetic circuits that produce different magnetic circuit intensities between the magnetic device and a ferromagnetic body.

[0174] In embodiments, method 700 comprises bringing a ferromagnetic body into contact with a second pole shoe, as depicted in block 704. In embodiments, the second pole shoe is attached to the same housing to which the first pole shoe is attached. In embodiments, the magnetic device may be in the first configuration when the second pole shoe makes contact with the ferromagnetic body.

[0175] In embodiments, method 700 comprises causing the magnetic device to change from the off state to an on state, as depicted in block 706. In embodiments, the transition of the magnetic device from the off state to the on state may comprise actuating (e.g., rotating) the second permanent magnet from a first position to a second position. Additionally, when the magnetic device is in an on state, the magnetic circuit is formed through the workpiece.

[0176] With reference to Figure 13, an example robotic system 700 is illustrated. Although a robotic system 700 is depicted in Figure 13, the embodiments described in relation to it can be applied to other types of machines, (e.g., crane hoists, pick and place machines, etc.).

[0177] The robotic system 700 includes an electronic controller 770. The electronic controller 770 includes additional logic stored in associated memory 774 for execution by the processor 772. A robotic motion module 702 is included that controls the movements of a robotic arm 704. In the illustrated embodiment, the robotic arm 704 includes a first arm segment 706 that can rotate about a base around a vertical axis. The first arm segment 706 is movably coupled to a second arm segment 708 via a first joint 710 in which the second arm segment 708 can rotate about the first arm segment 706 in a first direction. The second arm segment 708 is movably coupled to a third arm segment 711 via a second joint 712, in which the third arm segment 711 can be rotated relative to the second arm segment 708 in a second direction. The third arm segment 711 is movably coupled to a fourth arm segment 714 via a third joint 716, in which the fourth arm segment 714 can be rotated relative to the third arm segment 711 in a third direction, and a swivel joint 718 allows the orientation of the fourth arm segment 714 relative to the third arm segment 711 to be changed. The magnetic coupling device 10 is shown as an example secured to the end of the robotic arm 704. The magnetic coupling device 10 is used to couple a workpiece 27 (not shown) to the robotic arm 704. Although the magnetic coupling device 10 is illustrated, any of the magnetic coupling devices described herein, and any number of them, can be used with the robotic system 700.

[0179] In one embodiment, the electronic controller 770, via the processor 772 executing the robotic motion module 702, moves the robotic arm 704 to a first position in which the magnetic coupling device 100 makes contact with the workpiece at a first location. The electronic controller 770, via the processor 772 executing a magnetic coupler status module 776, instructs the magnetic device 10 to move the upper magnet 12 relative to the lower magnet 14 to place the magnetic coupling device 10 in the "on" state to couple the workpiece to the robotic system 700. The electronic controller 770, via the processor 772 executing the robotic motion module 702, moves the workpiece from the first location to a second, desired, spaced location. Once the workpiece is in the second desired position, the electronic controller 770, through the processor 772 running the magnetic coupler status module 776, instructs the magnetic device 10 to move the upper magnet 12 relative to the lower magnet 14 to place the magnetic coupling device 10 in an off state to uncouple the workpiece from the robotic system 700. The electronic controller 770 then repeats the process to couple, move, and uncouple another workpiece.

[0181] In one embodiment, the disclosed magnetic devices include one or more sensors for determining a feature of the magnetic circuit present between the magnetic device and the workpiece to be coupled to the magnetic device. Further details of example sensor systems are provided in U.S. Provisional Application No. 62/490,705, entitled SMART SENSE EOAMT, filed April 27, 2017.

[0182] Each of the magnetic coupling devices described above can be used in combination with a mechanical lifting apparatus that lifts and transports a ferromagnetic workpiece from a first location to a second location. Examples of mechanical lifting apparatus include mechanical gantries, crane hoists, stationary devices, robotic devices, etc.

Claims (15)

1. CLAIMS 1. A magnetic device (10, 100) for magnetically coupling to a ferromagnetic body (27), comprising: a casing (28, 104); a plurality of pole shoes (16', 16'', 102', 102'', 200, 300, 400) coupled to the housing, wherein a first portion of the plurality of pole shoes cooperates with the housing (28, 104) to form a first pole of the magnetic device (10, 100) and a second portion of the plurality of pole shoes (16', 16'', 102', 102'', 200, 300, 400) cooperates with the housing (28, 104) to form a second pole of the magnetic device, and wherein each of the first pole of the magnetic device (10, 100) and the second pole of the magnetic device (10, 100) includes a ferromagnetic body having a first portion positioned near the housing (28, 104) and a second portion including a plurality of spaced projections (44, 170', 170'', 206, 306, 406) that collectively form a workpiece contact interface (17', 17'', 132', 132'', 212, 312, 412) of the pole; a plurality of permanent magnets (12, 14, 118, 120) including a first permanent magnet (14, 120) supported by the housing and having a pair of active N-S poles and a second permanent magnet (12, 118) supported by the housing and configurable relative to the first permanent magnet (14, 120) to provide a first configuration, in which a north pole of the second permanent magnet (12, 118) is aligned with a north pole of the first permanent magnet (14, 120) and a south pole of the second permanent magnet (12, 118) is aligned with a south pole of the first permanent magnet (14, 120), and a second configuration, in which the north pole of the second permanent magnet (12, 118) is misaligned with the north pole of the first permanent magnet (14, 120) and the south pole of the second permanent magnet (12, 118) is misaligned with the north pole of the first permanent magnet (14, 120) south of the first permanent magnet (14, 120); and wherein the magnetic device (10, 100) establishes a first magnetic circuit with the first permanent magnet (14, 120) and the second permanent magnet (12, 118) through the plurality of pole shoes (16', 16'', 102', 102'', 200, 300, 400), when the second permanent magnet (12, 118) is in the first configuration, and a second magnetic circuit with the first permanent magnet (14, 120) and the second permanent magnet (12, 118), when the second permanent magnet (12, 118) is in the second configuration. 2. The magnetic device (10, 100) of claim 1, wherein the first magnetic circuit passes substantially through the first pole and the second pole to couple the ferromagnetic body (27) to the magnetic device (10, 100) and the second magnetic circuit is substantially confined within at least a portion of the housing (28, 104) and the plurality of pole shoes (16', 16'', 102', 102'', 200, 300, 400). 3. The magnetic device of any one of claims 1 and 2, wherein the workpiece contact interface (17', 17'', 132', 132'', 212, 312, 412) of the first pole extends along a lower end of the first pole, the lower end of the first pole having a first number of projections of the plurality of spaced projections (44, 170', 170'', 206, 306, 406) and a second number of recesses (46, 210, 310, 410) interposed between the first number of projections, the second number being at least two. 4. The magnetic device (10, 100) of claim 3, wherein the second number is at least three and optionally wherein the second number is at least five. 5. The magnetic device (10, 100) of any one of claims 3 and 4, wherein each of the recesses (46, 210, 310, 410) is dimensioned to prevent the ferromagnetic body (27) from entering the respective recess (46, 210, 310, 410) and optionally wherein at least one of the recesses (46, 210, 310, 410) has a width substantially equal to a depth of the at least one recess (46, 210, 310, 410). 6. The magnetic device (10, 100) of any one of claims 3-5, wherein each of the recesses (46, 210, 310, 410) has a respective profile extending between adjacent projections, the respective profile having a continuous slope. 7. The magnetic device (10, 100) of any one of claims 3-6, wherein at least one of the recesses (46, 210, 310, 410) has a depth substantially equal to a thickness of the ferromagnetic body (27) to be coupled to the magnetic device. 8. The magnetic device (10, 100) of any one of claims 3-7, wherein at least one of the recesses (46, 210, 310, 410) has a width substantially equal to a thickness of the ferromagnetic body (46, 210, 310, 410) to be coupled to the magnetic device. 9. The magnetic device (10, 100) of any of claims 1-8, wherein the plurality of pole shoes (16', 16'', 102', 102'', 200, 300, 400) are removably coupled to the housing (28, 104). 10. The magnetic device (10, 100) of any of claims 1-9, further comprising at least a compressible member (420) arranged between the plurality of spaced projections (406). 11. The magnetic device (10, 100) of any of claims 1-10, wherein the plurality of spaced projections form a nonlinear workpiece contact interface. 12. The magnetic device (10, 100) of any of claims 1-10, wherein the plurality of spaced projections form a linear workpiece contact interface. 13. The magnetic device (10, 100) of any of claims 1-12, wherein the second permanent magnet (12, 118) is movable relative to the first permanent magnet (14, 120), and further comprising the magnetic device (10, 100) an actuator operatively coupled to the second permanent magnet for moving the second permanent magnet relative to the first permanent magnet to a first position corresponding to the first configuration and a second position corresponding to the second configuration. 14. The magnetic device (10, 100) of any of claims 1-12, further comprising a plurality of wires (162) arranged around the second permanent magnet (12, 118), the second permanent magnet (12, 118) being selectively placed in one of the first configuration and the second configuration by applying a current to the plurality of wires, and the second permanent magnet (12, 118) being held in the selected one of the first and second configurations when the current is removed. 15. A robotic system (700) comprising a robotic arm (704) and a magnetic coupling device (10, 100) according to any one of claims 1-14 coupled to an end of the robotic arm (704).